Pluto in the 3rd House can be resumed as intellectual gluttony. It's a very interesting aspect as, someone with this position of Pluto just never seem to be satisfied with the knowledge they have, consistently seeking more. There is an inherent restlessness that nothing can soothe.
Here we find bookworms of course, but overall - there is someone who feels the need to categorize, classify, organize, name, learn, add, accumulate, overall; understand the world. The 3rd House is a house which isn't so concerned with discriminating new information, more so that it is concerned with always getting more: More perspectives, more content, more knowledge. As Pluto is compulsive and obsessional - it can become a sort of race for the person to always accumulate more. And accumulate is a key word here - When the 9th House is about assimilating, the 3rd House is more so about accumulating, and it is something to watch for with this position and why I used the word gluttony to begin this post.
The 3rd House wants omniscience, gathering ALL the knowledge so that, eventually one day, we can form an opinion that is full rounded, with "all the facts". The challenge with this position of Pluto is to make sure we find a sense of unity in the thought. The challenge is to learn how to accept that in order to have an opinion, a perspective, a belief, we do not need ALL the facts available to mankind, we only need relevant facts. Because the truth is this, depending on your belief, perspective and opinion (9th house) you will find facts (3rd House) that support it. Aiming for objectivity and thriving for more facts, in order to form an objective belief/opinion is a noble cause, but it's a pointless one. The truth is, there is just too many facts about any given subject to perceive them all. This is what a 3rd house Pluto is trying to grapple with.
The 3rd House is where we find thoughts patterns and communication, and with this position of Pluto there can be a tendency to monopolize the conversation, dominate the conversation, or speak more than you listen. You'll say - a lot of us do experience this issue, but Pluto in the 3rd House can become a very intent listener, capable of actually taking the time to hear what the other person has to say, and you know why? Because Pluto here can take listening as yet another activity to gather MORE FACTS.
Another great gift of Pluto in the 3rd House is one of curiosity - the same curiosity that push them to accumulate new knowledge, can be used for relationship skills - being curious, instead of judgemental or indifferent, to what other people think and/or have to say.
"Pluto an evolutionary journey of the soul": By Jeff Green
"The book of Pluto": Steven Forrest